The word "Ianuarius"'s the original Roman designation of the month January. The name's either derived from the two-faced Roman god Janus, from the Latin word ianua, which means "door", or it's the masculine form of Diana, which would be Dianus or Ianus (Janus). The 12 Roman month names are: Martius, Aprilis, Maius, Iunius, Quintilis (later Iulius), Sextilis (later Augustus), Septembris, Octobris, Novembris, Decembris, Ianuarius, and Februarius. Latin phrases for the days in Ianuarius (January… (More on Ianuarius)